interstitial fluid

Examples of interstitial fluid in the following topics:

• Open and Closed Circulatory Systems

  • The blood is called hemolymph because it mixes with the interstitial fluid.
  • (a) In closed circulatory systems, the heart pumps blood through vessels that are separate from the interstitial fluid of the body.
  • (b) In open circulatory systems, a fluid called hemolymph is pumped through a blood vessel that empties into the body cavity.

• Flame Cells of Planaria and Nephridia of Worms

  • The cilia propel waste matter down the tubules and out of the body through excretory pores that open on the body surface; cilia also draw water from the interstitial fluid, allowing for filtration.
  • The ciliated tubules filter fluid from the body cavity and carry waste, including excess ions, through openings called nephrostomes.
  • In (b) annelids, nephridia filter fluid from the body cavity.

• Malpighian Tubules of Insects

  • The system of malpighian tubules consists of branching tubules, which increase their surface area, near the hemolymph (a mixture of blood and interstitial fluid that is found in insects, other arthropods, and most mollusks) and fat tissues.
  • Body fluids are not filtered, as in the case of nephridia.

• Plasma and Serum

  • Serum, the plasma component of blood which lacks coagulation factors, is similar to interstitial fluid in which the correct composition of key ions acting as electrolytes is essential for normal functioning of muscles and nerves.

• Kidney Function and Physiology

  • Kidneys' osmolarity of body fluids is maintained at 300 milliosmole (mOsm).
  • Water flows from the filtrate to the interstitial fluid, so osmolality inside the limb increases as it descends into the renal medulla.
  • At the bottom, the osmolality is higher inside the loop than in the interstitial fluid.

• Introduction to Osmoregulation

  • The intake is balanced by more or less equal excretion of fluids by urination, defecation, sweating, and, to a lesser extent, respiration.
  • The solutes in body fluids are mainly mineral salts and sugars.
  • The body's fluids include blood plasma, the cytosol within cells, and interstitial fluid, the fluid that exists in the spaces between cells and tissues of the body.
  • Mammalian systems have evolved to regulate osmotic pressure by managing concentrations of electrolytes found in the three major fluids: blood plasma, extracellular fluid, and intracellular fluid.
  • Water movement due to osmotic pressure across membranes may change the volume of these fluid compartments.

• Arteries, Veins, and Capillaries

  • Fluid also crosses into the interstitial space from the capillaries.
  • Fluid is also brought back to the heart via the lymphatic system.

• Male Reproductive Anatomy

  • The male reproductive system is a series of organs and glands that produce sperm, fluids, hormones, and enable the ejaculation of sperm.
  • Other cells mixed in the wall of the tubules are the interstitial cells of Leydig; these cells produce high levels of testosterone once the male reaches adolescence.
  • An ejaculate will contain from two to five milliliters of fluid with from 50–120 million sperm per milliliter.
  • The bulbourethral gland, or Cowper's gland, is an exocrine gland which secretes a clear fluid known as pre-ejaculate that is generated upon sexual arousal.
  • This usually accounts for a couple of drops of fluid in the total ejaculate and may contain a few sperm.

• Cytotoxic T Lymphocytes and Mucosal Surfaces

  • Lymph, the watery fluid that bathes tissues and organs, contains protective white blood cells, but does not contain erythrocytes (red blood cells).
  • Cells of the immune system can travel between the distinct lymphatic and blood circulatory systems, which are separated by interstitial space, by a process called extravasation (passing through to surrounding tissue).
  • (a) Lymphatic vessels carry a clear fluid called lymph throughout the body.

• Fluid Mosaic Model

  • The fluid mosaic model describes the plasma membrane structure as a mosaic of phospholipids, cholesterol, proteins, and carbohydrates.
  • The fluid mosaic model was first proposed by S.J.
  • The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components —including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character .
  • Therefore, phospholipids form an excellent lipid bilayer cell membrane that separates fluid within the cell from the fluid outside of the cell.
  • The fluid mosaic model of the plasma membrane describes the plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins.